Bubble Size Characterization in Liquid-Filled Pipes Based on Electromagnetic Acoustic Guided Waves

Characterizing bubble size in gas-liquid two-phase flow based on the relationship between ultrasonic pulse energy and bubble size is essential for understanding the flow process and optimizing gas-liquid two-phase flow systems. However, due to the harsh working environment, precise bubble size measurement presents significant challenges. Given the strong adaptability of electromagnetic ultrasonic technology in harsh working environments, this paper proposes a method for bubble size characterization based on EMAT-generated ultrasonic guided waves. Considering the attenuation characteristics of guided waves energy, the L(0,1) wave mode was selected, and the excitation frequency of 348 kHz is determined based on the phase velocity curve. The finite element method was used to validate the leakage waves theory and the effectiveness of the proposed method. The received signal was processed in the time domain, where the ultrasonic energy was obtained by integrating the signal within a predefined time window, and a quantitative relationship between different bubble diameters and ultrasonic energy was established. An electromagnetic ultrasonic fluid detection device was constructed, with two sets of electromagnetic acoustic transducer arrays circumferentially arranged around the fluid-filled pipeline, for exciting and receiving ultrasonic waves respectively. The results indicate that there is a functional relationship between received signal energy and bubble diameter, with the maximum error between the fitted curve and the actual values being 3.39%. Both simulations and experiments validate the effectiveness of the method proposed in this paper, enabling the measurement of bubbles with different diameters.